The invention relates to a method and an apparatus for bonding together at least two running lengths of material using at least one continuous or interrupted strip of adhesive applied to at least one of the running lengths or web.
So far a comparatively viscous adhesive or glue has been used, that is to say one whose viscosity is substantially higher than that of water, normally by a factor of almost twenty. Accordingly comparatively high pressures are required for the application of the adhesive to the work. Normally pressures of the order of 5 bar are used and the consequence of this is that special pressure containers are required, into which the adhesive has to be charged. A further and more particularly significant disadvantage is that on transferring the adhesive from the commercial shipping drum into the special adhesive container particles of dirt may become mixed with the adhesive and that on the one hand there is no provision for filtering the adhesive since the filter required for this would be much too large in size and also elaborate in construction. The undesired consequence of this is on the other hand that the applying means have to have a comparatively large adhesive feed hole, this in turn leading to the disadvantage that the applied strip of adhesive is relatively thick. The result of this is accordingly not only a high rate of adhesive consumption but also fouling of the machine and in the case of the bonding together of running lengths of paper which are to be made into folded products the transverse cutter, which is used to cut by the package of running length or web may well be soiled. Accordingly as a matter of experience it is necessary to interrupt production from time to time and to clean the parts of the machinery coming into contact with the adhesive. A further factor to be considered is that owing to the absence of means for filtering the adhesive that, despite the provision of a large adhesive feed hole, blockage of the feed system is prone to occur, something that also leads to an interruption of production.